How are setting the grain bed if you keep stirring it while you drain? Fly or batch sparging, you still need the have the grain bed set and act as a filter. Grain bed should only stick if it being compacted or using large amounts or wheat.
The vinegar is from a bacterial contamination. To me there is a very distinct difference between acid tartness and vinegar. If it really is vinegar it will get worse. If you transfer you must transfer to a container that has less head space, like a carboy. I also think 2 weeks is too soon to...